Physical Activity Buffers the Effects of Chronic Stress on Adiposity in Youth Zenong Yin, Ph.D., Catherine L. Davis, Ph.D., Justin B. Moore, Ph.D., and Frank A. Treiber, Ph.D. Georgia Prevention Institute, Department of Pediatrics Medical College of Georgia ABSTRACT Background: The moderating effect of physical activity (PA) on relations between chronic stress and adiposity is unknown in youth. Purpose: The objective is to assess the mediating effect of PA on relations between stress and adiposity in youth. Methods: Participants were 303 youths (47% Black, 53% White, 50% male, M age = 16.6 years). The Adolescent Resource Challenge Scale assessed personal stress, whereas median rent or mortgage in the neighborhood reflected community stress. Body mass index (BMI) and sum of skinfolds reflected general adiposity, and waist circumference measured central adiposity. Days per week per- forming PA sufficient to work up a sweat measured PA. Results: Hierarchical regressions predicted each adiposity measure ad- justing for age, race, gender, family socioeconomic status, and parental smoking. Independent contributions of personal stress, but not community stress, were found on BMI and sum of skin- folds. A similar model showed that both personal and community stress predicted waist circumference. PA was independently, in- versely associated with sum of skinfolds but not BMI or waist cir- cumference. The interaction between PA and personal stress pre- dicted all three adiposity measures. The interaction of PA with community stress predicted BMI. Conclusions: PA appears to buffer the effects of chronic stress on adiposity, providing evi- dence that PA is a protective factor for health. (Ann Behav Med 2005, 29(1):29–36) INTRODUCTION Over the past 2 decades, American youth became twice as likely to be overweight as increasing trends of sedentariness and consumption of energy-dense foods were observed (1–3). In addi- tion to deleterious effects on physical health, overweight in adoles- cents also could have long-term social and economic impacts (4). Evidence from clinical, epidemiological, and basic re- search accumulated over the past 20 years has clearly demon- strated physical activity (PA) of a moderate intensity can en- hance overall health in youth and that increased intensity confers greater benefits (5). The benefits associated with moder- ate to vigorous PA include reduced risk for cardiovascular (CV) disease and improved glucose metabolism, strength, CV fitness, self-esteem, and body image (5). In a cross-sectional survey of 9,957 adolescents in Grades 7, 9, and 11, overweight adolescents reported engaging in sig- nificantly more unhealthy behaviors (e.g., unhealthy eating hab- its, watching more TV, and exercising less often) and experienc- ing greater levels of emotional distress (6). Other researchers also found similar relations between being overweight and problems in unhealthy diet and PA habits, social relations, school experiences, and psychological well-being (7,8). Stress has been tied to obesity in children and adolescents. Psychological stress has been shown to precede weight gain (9,10). Living in a neighborhood at the lower end of the socio- economic continuum can cause greater stress due to the in- creased burdens of coping with limited resources and negative life events for a prolonged period of time. Limited access to health-related resources such as health care and preventive pro- grams can affect residents’ health and health behavior (11). In- dividuals living in a disadvantaged community may have lim- ited access to opportunities for PA and healthy eating (12,13). The mechanisms through which stress may influence obe- sity have not been fully elucidated. Behaviorally, stress is thought to contribute to obesity through lifestyle choices while under stress. It has been demonstrated that women tend to prefer high fat or sweet foods when moderately stressed (14) and that the administration of cortisol in healthy men dramatically in- creased food intake (15). A review of the stress-induced eating literature found a consistent link between stress and overeating in adults, especially in those who are restrained eaters (16). This has been demonstrated recently in children (17) in response to laboratory stressors. The effects of stress on adiposity via such dietary behaviors may be buffered by PA increasing energy ex- penditure or diminishing negative affect or both. Steptoe, Wardle, Pollard, Canaan, and Davies (18) found that college students in a high stress condition decreased PA compared to nonstressed controls, which lends further support for a direct ef- fect of stress causing inactivity. Health behaviors tend to cluster, such that individuals who habitually exercise and eat a healthy diet are likely to be non- smokers and to drink alcohol in moderation; such people tend to be in higher socioeconomic strata (19,20). Exposure to second- ary smoke has been associated with health indicators in chil- dren, including physical inactivity and higher body mass index (BMI) (21). Compared to youth with greater resources, risk-moderating effects are most apparent for youth with few resources. A re- source is “protective” when it only operates in the presence of a risk and mitigates its negative effect (22). On the other hand, a 29 The research was supported by National Institutes of Health Grant HL69999. These results were presented as a poster at the Annual Meet- ing of the Society of Behavioral Medicine, Salt Lake City, Utah, March 21, 2003 and published as an abstract in Annals of Behavioral Medi- cine, 2003, 25(Suppl.):S082. Reprint Address: Z. Yin, Ph.D., University of Texas San Antonio, De- partment of Health and Kinesiology, 6900 North Loop West, San Antonio, TX 78249. E-mail: zenong.yin@utsa.edu © 2005 by The Society of Behavioral Medicine. Downloaded from https://academic.oup.com/abm/article/29/1/29/4631626 by guest on 29 September 2023